Shop Setup in Outdoor Shed - Opinions Requested

Hey everyone, when we bought our new house a couple years ago it came with a prefabbed 12’x12’ shed in the back (identical to this one ) that the previous owner had installed a sub meter to. Instantly I figured it would be the spot for my modest shop. So far it’s been just been left entirely as is as a storage space with me just pulling tools out into whatever floor space I can find. Now that it’s time to actually turn it into a shop, there are a few topics that I was hoping to get some opinions on from those with more experience that myself and those that operate in a similar situation. For climate reference, I live in Northern Va, outside of DC.

Moisture control:Since the shed is only 12×12, I’d like to condition the space with a small window ac unit mounted in the rear wall out of the way. Less than 150sf should be a pretty minimal load. However, my concern here is the general moisture prevention. In an ideal world, if I had built the shed from the ground up I would’ve installed a plastic vapor barrier between the studs and the siding. However, the prefab construction is simply ply on 2×4 with an exterior coat of paint. It doesn’t leak, but of course it’s not enough to really prevent moisture from coming in with the humidity. I’ve looked for a paint on VB that I could put up before I insulate the space with either roxul or rigid foam panels, but everything I’m coming across is rated for masonry or drywall and won’t claim to provide a VB rating if applied on wood. The only stuff I’ve come across is HydroLock which is exorbitantly priced…I could practically take off the sheathing and reinstall for the same price (I DON’T want to take off the exterior for the record). My major concern is keeping the space dry enough to keep the wood stable and keep the rust at bay. Is the concept of a VB overkill? Roxul is considered water repellant so I’m not too worried about mold I don’t think. Is there a more effective way to keep the moisture levels down as opposed to running the AC full time? That would seem like a pretty big waste of energy/money.

Dust control:I’ve read through the Bill Pentz gospel and regardless as to whether I tend to think he is a bit overzealous in his discussion, the smallest shop size he tends to talk about is a 2 car garage – that’s 4x the size of the shop space I’ve got. I managed to pick up a 1hp delta dc for what I’d consider free. A 5hp setup and 6” ducts seems like ridiculous overkill for less than 150sf. My thought was to plumb out some rigid 4” to each side (workbench on one side and tool stations on the other) and one to be in the center of the shop to plug into my table saw, floor vacuum, whatever (this one seems unnecessary as I could easily pull a hose from one of the blast gates on the side). With a small 1hp unit I’d have one gate open at a time to maintain enough cfm to pull the bulk of the materials and some dust. Potentially a cyclone/thein baffle, but the bigger question would be venting outside vs buying a filter. I’m using a mask now that I’d probably still keep around if I was doing sanding work.

Concerns with the filter: takes up more space. Concerns with venting outside: that would be a gap in the insulation envelope and in such a small space I’d lose my conditioned air pretty quick.

I’d likely try to get an air filter in there as well but space would start to get tight.

For ducting reference, here’s the layout that I was working with so far for my space (this doesn’t account for a bandsaw that is now in my possession…oops?)

As I mentioned, happy to get some insight on any of it, all of it, whatever, from those who have similar setups.

I work in a 12×16 outdoor shed. Some of these you are probably already planning but I’ll mention them anyway.1. Depending on the foundation, you might want to beef up the floor. If the shed is raised, add floor joists. If you can’t reach the floor joists, put down an extra layer of 3/4” ply. Sheds aren’t really built to hold a lot of weight and the floor can get bouncy. 2. Run wiring under the floor and install a floor receptacle in the center of the room. 3. Insulate and put a vapor barrier between the insulation and wallboard. My shop is not insulated, nor has a vapor barrier, Eastern NC is basically one big swamp, and I have no moisture issues. But my shop is raised off the ground.4. A window unit AC is doable but the filter will clog with dust much quicker. A small heat pump would be less expensive and more efficient. Provide heat and cooling. You don’t need the shop much above 65 in the winter. 5. I have a 1hp DC + 20’ hose and move the hose from machine to machine. If starting from scratch I would plumb it with PVC.6. Put your outlets at elbow height, about 4’ apart. Put in way more than you need. Run multiple circuits so the top plug is on one circuit, the bottom plug on another. Run dedicated circuits to big machines. Hope you find that somewhat helpful.

I don’t think I would worry too much about moisture. Your heat will take care of it in the winter and your window unit will take care of it in the warm months. The problem with moisture in a small shop like you have, and you can see it better with a humidity gauge, is that you get the place all down to 50%, open the door one time to go inside and see the meter jump to 75%-80%. I would not worry about moisture barrier in a shop that small for this reason. How far is the run from your sub panel {you said sub meter? What is a sub meter?} to the source {your main panel in the house?} Verify that the proper gauge wire was used for the distance covered. Often these things are wired by the previous home owner and he is probably not an electrician. There are a lot of well meaning folks out there that know enough to get themselves or others into trouble. He could have wired it too light and what he was doing worked fine, now you set up some machines with a higher demand and run into trouble. Double check.As far as dust control, on an outside unit you are going to need a plumbed air intake in a room that small, unless you use a self contained style DC. I live in southern Maryland and our climates are probably identical. My shop is 30X30 steel building and I use a window AC unit mounted permanently in the wall. I don’t know of a heat pump that is “cheaper”...maybe cheaper to run, no argument…but cheaper to buy? Doubt it, then there’s a floor space issue for the handler. I use a self contained dust collector that I roll around and hook to each machine. Permanent plumbed in outdoor units are nice, but the cost goes way up and on a 12X12? The only reason to put it outside would be the limited space. I think I’d built a little dry vac “shack” outside and run a long hose thru the wall. Best of luck!!! Check that feed line.

Vapor barrier needs to be toward the conditioned space, not on the exterior wall. So forget painting the inside of the siding. Just put up fiberglass batt insulation and cover it with sheet rock or 1/4 inch plywood/paneling.

A 5k btu window air conditioner and a 1500 watt electric heater will be all you need for summer and winter.

I’d build a workbench across one wall. Forget the dust collector, use a shop vac under the bench. Put other tools on wheels so you can move them around as needed. Add some lights, and a couple electrical outlets. You’re good to go at that point.

-- Murphy's Carpentry Corollary #3: Half of all boards cut to a specific length will be too short.

I don t think I would worry too much about moisture. Your heat will take care of it in the winter and your window unit will take care of it in the warm months. The problem with moisture in a small shop like you have, and you can see it better with a humidity gauge, is that you get the place all down to 50%, open the door one time to go inside and see the meter jump to 75%-80%. I would not worry about moisture barrier in a shop that small for this reason. How far is the run from your sub panel {you said sub meter? What is a sub meter?} to the source {your main panel in the house?} Verify that the proper gauge wire was used for the distance covered. Often these things are wired by the previous home owner and he is probably not an electrician. There are a lot of well meaning folks out there that know enough to get themselves or others into trouble. He could have wired it too light and what he was doing worked fine, now you set up some machines with a higher demand and run into trouble. Double check.As far as dust control, on an outside unit you are going to need a plumbed air intake in a room that small, unless you use a self contained style DC. I live in southern Maryland and our climates are probably identical. My shop is 30X30 steel building and I use a window AC unit mounted permanently in the wall. I don t know of a heat pump that is “cheaper”...maybe cheaper to run, no argument…but cheaper to buy? Doubt it, then there s a floor space issue for the handler. I use a self contained dust collector that I roll around and hook to each machine. Permanent plumbed in outdoor units are nice, but the cost goes way up and on a 12X12? The only reason to put it outside would be the limited space. I think I d built a little dry vac “shack” outside and run a long hose thru the wall. Best of luck!!! Check that feed line.

- msinc

You’re correct, sub-panel, not sub-meter. That’s what happens when your brains running at 1am. As to the run, that actually was a point of contention at closing, they paid to have an electrician come and run an appropriately sized line.

Most points seem to be aligned with what I’ve got in mind. I’ve got a series of outlets at regular height, but I plan on installing shop height setups. While everything will be on casters, my game plan is to have everything in a “semi-permanent” location with flip top tables and only move them out if necessary. Center outlet in the floor is a good idea.

In regards to the AC/humidity, my concern isn’t as much about when I open the door the handful of times since the CF of the space isn’t that high/gets swapped out relatively frequently, but more about the rest of the week when I’m not in there… The general consensus however seems to be that a moisture barrier isn’t necessary?

An “out building” isn’t really an option where it’s located unfortunately, which would extend to a split unit system sitting out beside it. I could maybe consider hanging a smaller unit – something like a Climateright system looks pretty cool, but pricey (I was originally looking at craigslist window units for price reference lol)

I thought you stated that you have insulation, dont have a vapor barrier and you don’t have moisture issues. In rereading I saw you still recommended a VB, why is that if you have success without it? My shed is an inch or 2 off the ground up front and about 8” in the back.

With respect to dust, it seems to me the amount of dust generated is related to the work done, not the size of the space, and the density of dust in the air would actually be inversely proportional to the square footage, so applying Penz’s 2-car garage ratio….. maybe you need 10 HP and 12” ducts. And if you vent that outside, then you can forget about heating or cooling issues, as you’ll be replacing 100% of the air in the shed every 3 milli-seconds.

I thought you stated that you have insulation, dont have a vapor barrier and you don’t have moisture issues. In rereading I saw you still recommended a VB, why is that if you have success without it? My shed is an inch or 2 off the ground up front and about 8” in the back.

- SamV

I could have probably used more words but basicallyinsulate = vapor barrierno insulation = no need for vapor barrierThe vapor barrier is not for your tools, it’s for the structure. It prevents condensation inside the walls where warm meets cold. Sometimes people complain that the drywall in their shop gets mold or mildew, that’s probably because of condensation. Skipping the VB might be fine in a building that small, I don’t know what your plans are for heating it. A space heater will work but if you run it all the time it will be expensive compared to a heat pump. And if you only run it when you need it, there is a risk of condensation when the air cools down again. Any gas heat will introduce a lot of moisture.

I suspect that my shop being all wood and uninsulated helps regulate the humidity inside as I have no rust problems but many other woodworkers in the area do. Or maybe it’s because I’m off the ground and moisture can’t come through the earth into the shop. Or probably both. The downside is my shop is cold all the time and a heater is barely effective. So whatever tradeoffs come with insulation, I would take them.

I thought you stated that you have insulation, dont have a vapor barrier and you don’t have moisture issues. In rereading I saw you still recommended a VB, why is that if you have success without it? My shed is an inch or 2 off the ground up front and about 8” in the back.

- SamV

I could have probably used more words but basicallyinsulate = vapor barrierno insulation = no need for vapor barrierThe vapor barrier is not for your tools, it s for the structure. It prevents condensation inside the walls where warm meets cold. Sometimes people complain that the drywall in their shop gets mold or mildew, that s probably because of condensation. Skipping the VB might be fine in a building that small, I don t know what your plans are for heating it. A space heater will work but if you run it all the time it will be expensive compared to a heat pump. And if you only run it when you need it, there is a risk of condensation when the air cools down again. Any gas heat will introduce a lot of moisture.

I suspect that my shop being all wood and uninsulated helps regulate the humidity inside as I have no rust problems but many other woodworkers in the area do. Or maybe it s because I m off the ground and moisture can t come through the earth into the shop. Or probably both. The downside is my shop is cold all the time and a heater is barely effective. So whatever tradeoffs come with insulation, I would take them.

I have a small shop so I put my dust collector in a different shed and duct it to my shop. The issue of losing conditioned air, here in this high desert, in West Texas, is an important consideration. I have a 6” duct to each tool and at the two that I use the most I installed a 6” duct to the outside with a blast gate at the tool. Now the air comes in right at the tool and exits right at the tool taking the dust out to the dust collector. This make up air works well for me summer and winter. I cool my 13’x23’ shop with two window units.